In the existing electric motor control system for driving a main shaft by an electric motor, two encoders are generally required. One of the encoders is arranged in the electric motor for feedback of the rotational speed of the electric motor, and the other encoder is arranged at a main shaft in transmission connection with the electric motor for feedback of the rotational position of the main shaft. The electric motor control system can control the electric motor according to the above-mentioned rotational speed of the electric motor and the rotational position of the main shaft.
In some working environments, a relatively high control precision of the main shaft is required, and high-resolution encoders are often required for the above-mentioned two encoders.